The Jeffers plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
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72° on Nov. 14, 1999, the hottest reading for this week of the year since 1918. Next is 70° in 2016.
Jeffers’s center stands about 4,940 ft above sea level. Within three miles the land runs from 4,850 ft to 5,340 ft, a difference of 490 ft: hilly country. The highest named summit within 15 miles is Lone Mountain, about 11,120 ft, 13 miles east-southeast.
Under the town center the state geologic map shows Alluvium (gravel, sand, silt), from the Pleistocene to Holocene, less than 1.8 million years old.
The section below crosses 16 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 3×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gneiss. Age: Archean. About 7 mi of the line.
Gravel, sand, silt. Age: Pleistocene to Holocene, less than 1.8 million years old. About 5 mi of the line.
Unconsolidated. Age: Pleistocene to Holocene, less than 1.8 million years old. About 4 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 2 mi of the line.
Shale, sandstone. Age: Late Cretaceous, 84 to 100 million years old. About 1 mi of the line.
Gneiss, amphibolite. Age: Archean. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 10 smaller units along the line are not listed.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.
A raindrop that lands in Jeffers reaches the Gulf of America by way of Cedar Creek, the Madison, the Missouri and the Mississippi: about 3,530 river miles.
Lakes on the way: Lake Oahe, Lake Sakakawea, Lake Fort Peck and Lake Sharpe.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Jeffers; river miles along the main stem, rounded.
Jeffers has a warm-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 15° in January. A normal year brings about 45 inches of snow; with the rain, that comes to about 13 inches of water.
On November 14 Jeffers normally reaches 43° and falls to 22°. The record high is 72°, in 1999; the record low −15°, in 1978. The most rain on this date, 0.38 in, fell in 2017.
Normals 1991–2020 and records since 1918 at Ennis, here. NOAA, through RCC-ACIS.
